Although electronic imaging chips, such as CCDs, have found extensive use in electronic imaging devices, their utilization in endoscopes has been limited because of size. The trend is to make endoscopes of ever decreasing diameter so as to be less intrusive when introduced into the body of a patient. However, the ability to reduce the diameter of the endoscope is often controlled by the size of the imaging device. The standard CCDs do not allow for miniaturization in their present configuration. Because of their relatively large size, stereoscopic imaging, especially, has not been possible in a small endoscope. In order to overcome the relatively large size of the CCD they have often been positioned longitudinally within the endoscope and used either for side viewing or in combination with a prism to provide end viewing, all of which adds to the complexity, weight, cost and ultimate size.
Examples of attempts to compensate for the large sized standard CCDs in stereoscopic endoscopes are illustrated in a number of patents.
Tasaki et al., U.S. Pat. No. 3,520,587, discloses a stereoscopic endoscope having two flexible fiber optic systems with objective lens systems being located at the distal end of each for focusing an image of the site to be inspected. An ocular is located at the proximal end of each fiber bundle for viewing the transmitted images. A visual perception in three-dimension is thereby created. This device is intended to provide a stereoscopic endoscope of limited diameter, but because of the use of light fibers for both transmitting and receiving light and the requirement for relatively sophisticated electronics, the device is still larger than desired for many applications and is quite costly.
Yabe, U.S. Pat. No. 4,786,965, discloses a conventional electronic chip structure in which a base plate is positioned behind the chip. This base plate as an extended side portion to which the leads on the chip are connected. This requires the endoscope to be of sufficient diameter to accommodate the extended side portion. Light is not transmitted through the base and it has no light transmitting qualities.
Miyazaki, U.S. Pat. No. 4,926,257, discloses a stereoscopic endoscope comprising a single solid-state image sensor and an optical image system. Stereoscopic imaging is made possible by shifting the solid-state image sensor .back and forth between the two optical imaging systems. A prism system is provided in which images are sequentially transmitted to provide the three-dimensional image for viewing.
Jones, Jr. et al., U.S. Pat. No. 4,924,853, also discloses a stereoscopic endoscope using a single imaging lens whereby the image is split by a split beam prism, which images are converted to electrical signals and displayed on a television screen. The images are transmitted from the lens by means of coherent light transmitting elements. This device also provides for the alternate transmission of images to provide a three-dimensional image for viewing.
Yajima et al., U.S. Pat. No. 4,862,873, discloses a stereoscopic endoscope comprising a pair of optical guides which are capable of conducting and illuminating light to be reflected on the site to be observed. While one optical guide conducts the illuminating light, the other optical guide conducts the light from the object being observed. The optical guides can be switched from one function to the other, thereby creating a stereoscopic image.
Tsujiuchi et al., U.S. Pat. No. 4,895,431, discloses a stereoscopic endoscope in which a first endoscope image is taken at one position while a second endoscopic image is taken from a second position. The endoscopic images are partially overlapped with means for detecting the relationship between the first and second images, thereby providing a three-dimensional image.